docs: def install_cmd(argv):
      '''Use Pythonz to download and build the specified Python version'''
      installer = InstallCommand()
      options, versions = installer.parser.parse_args(argv)
      if len(versions) != 1:
          installer.parser.print_help()
          sys.exit(1)
      else:
          try:
              actual_installer = PythonInstaller.get_installer(versions[0], options)
              return actual_installer.install()
          except AlreadyInstalledError as e:
              print(e)